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The interaction of micron-sized particles of nickel oxide with pieces of stress-recrystallized pyrolytic graphite has been studied between 950 and 1000°C using optical and scanning electron microscopy. The gases evolved (CO and CO 2 ) upon reduction of NiO to nickel were continuously pumped out of the system in most of the runs. Examination of the cleavage (basal) surface and prismatic (edge)...
Changes in the curing properties of matrix epoxy resin and the dynamic viscoelastic properties of the composites have been studied for the purpose of research on the properties-change mechanism of composites depending on the surface modifed reinforcing fibers. The dynamic viscoelastic properties of the composites using the surface modified carbon fibers by photo-oxygenation were measured by torsional...
The synthesis of a boron-substituted polyaromatic mesophase was studied by copyrolysis of a filtered coal tar pitch with pyridine-borane under a 1 MPa argon atmosphere. The pyrolysis temperature was varied between 360 and 420°C, the boron content of the pitch-pyridine-borane mixture was increased step by step up to 5%. Pyridine-borane is decomposed above 120°C; the pyridine is volatilized, and the...
The surface micro-structure of several carbon fibers with different mesophase contents (Mc, <10, 80 and 100%) and heat treatment temperatures (carbonization and graphitization) were studied by scanning tunneling microscopy (STM) at atomic resolution. At the carbonization temperature (1000°C), the low Mc fiber (<10%) surface remain largely amorphous while the crystalline structure is well developed...
In order to obtain basic data for the manufacture of porous carbon materials from various woody wastes, porous carbons were prepared from wood of the Japanese cypress by carbonizing at 900°C and the effect of holding time at 900°C on the properties of the carbons obtained was examined. A slight amount of air entered the vessel for carbonization during the heat treatment at 900°C and an activation...
Thin films of graphite were formed by chemical vapor deposition using two kinds of precursors, 2, 6-di (2 , 6 -dimethyl-1 naphthoyl)-naphthalene (0), and 2-methyl-1,2 naphtylketone (II). Structures of the films were studied by x-ray diffraction and Raman scattering spectra. The graphite formation temperatures on Ni using (0) and (II) were found to be above 800°C and 600°C, respectively. When...
Carbon thin films were prepared from decacyclene on quartz substrates with a chemical vapor deposition (CVD) process at 900°C under various conditions. The thickness and the electrical conductivity of these carbon thin films were measured by analytical instruments. As a result, it was found that the thickness of the obtained carbon thin films was controlled in the range of 0.1- 1.5mm by changing...
Methods of generation, diagnosis, control and application to carbon materials on cold plasmas are related from the standpoint of techniques for adding useful functions to carbon surfaces by the plasmas. Cold plasma has been used in many fields, such as semiconductor fabrication, diamond synthesis and surface improvement of various materials. In case of using cold plasmas, it is necessary to know...
The universally used assumption of proportionality between reaction rate and pore surface-area is modified for application to solids dominated by micropores, where it is shown that the discreteness of the solid phase necessitates some corrections. A new discrete random pore model, which modifies the earlier random pore model results, is proposed for such solids. An exact method and two other approximate...
Two anthracites (La Mure, France and Hongay, Vietnam) have been exfoliated after intercalation in a perchloric and nitric acid solution followed by a thermal shock treatment. The anthracites are extensively exfoliated as shown by scanning electron microscopy, and this treatment is responsible for a significant development of mesoporosity and a great increase of specific surface area. Hongay anthracite...
The compressive fracture processes in flat woven carbon fabrics reinforced carbon composite materials (C/C composites) were studied in-situ by means of optical microscopy. The compressive fracture strength obtained was 110MPa and 90MPa for the C/C composites with the final heat treatment at 1873K and 3273K, respectively. For the former composite, the specimen size dependence of fracture strength...
The burning-off characteristics by joule heating of mesophase pitch-based carbon fibers (MPCFs) in air have been studied, in order to evaluate the current capacity for electrical applications of the fibers. It is indicated that MPCFs have very high current capacity, as around 2.5 * 105 J/mm 2 , up to burning-off by joule heating, increasing with modulus of the fibers. The cross-section...
Chemical activation of a Washington state lignite was studied using heat-treatment temperatures (HTT) between 250 and 650°C. Thermal blanks were generated under similar conditions for comparison. Changes in chemical composition of both the thermal and acid-treated carbons were followed by elemental analysis and FTIR spectroscopy. With increasing HTT, acid-treatment promotes a more extensive loss...
Adsorption isotherms are obtained for the charcoal-nitrogen system in the temperature range 79-320 K and pressures to 5 MPa for two samples of activated charcoal. Correlations relating temperature dependence of adsorption potential are obtained using four methods of extrapolating pseudo-saturation state beyond the critical point. The values obtained are compared with literature data. Using the...
Oxidative stabilization studies on PAN-based copolymer fibers indicate the presence of at least two distinct reactions occurring at temperatures below 380°C. Techniques such as thermal stress, percentage shrinkage, differential scanning calorimetry, wide-angle X-ray diffraction and small-angle X-ray scattering have been used to elucidate the mechanisms involved. Reactions initiate in the amorphous...
This work presents the technology of thin carbon-carbon composite shells. Composites produced using Thornel P-100 high-modulus fibers were irradiated with γ-rays and neutrons. The influence of irradiation on flexural modulus was studied. The results indicate that the doses 10 Mrad and 6.1 10 16 n/cm 2 of γ-rays and neutrons, respectively, cause a slight increase in the elastic...
The force-displacement response of pyrolytic graphite, glassy carbon and coke with spherical tipped indenters is examined. The force-displacement behaviour for all these materials exhibits almost complete recovery with significant hysteresis between loading and unloading, the extent of which varies with material. Methods are discussed whereby the hysteretic indentation results may be interpreted...
Unidirectional carbon/carbon composites have been prepared using high strength and high modulus carbon fibres as reinforcements and phenolic, polyfurfuryl alcohol and furfuryl-siloxane resins as matrix precursors. The composites were pyrolyzed to 1000°C and subsequently heat treated to 1450 and 2800°C in the presence of argon. Changes in volume and density were measured and were found to be dependent...
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